More than 250,000 people are infected with hepatitis B virus in the U.S. every year. Infection is most common in young adults who are sexually active or work in hospitals and medical laboratories. Hepatitis B virus damages liver cells, causing the release of liver enzymes into the blood. Vaccination against hepatitis B virus is recommended because it's effective in preventing infection.
Hepatitis B Virus Infection
When hepatitis B virus enters the blood, it finds its way to the liver and invades liver cells, taking control of them. In the cell, hepatitis B virus can either make copies of itself or remain dormant for a while. When hepatitis B virus replicates itself, it eventually breaks through the cell, causing the release of liver enzymes from the cell. Elevated liver enzymes in the blood is evidence for liver cell damage. Hepatitis B virus infection can be acute or chronic. Acute infection is associated with greater symptoms over a short time. Chronic infection occurs over longer periods and causes more damage to the liver. Chronic infection can lead to liver cirrhosis, or hardening and shrinking of the liver. People with chronic infections are also at risk for hepatocellular carcinoma or cancer of the liver.
Symptoms of Infection
Hepatitis B virus causes inflammation, or irritation, of the liver. When the liver is irritated, it swells up, causing abdominal pain. Infection may also present with dark urine and jaundice. Patients may complain of nausea and vomiting, and sometimes diarrhea. Most symptoms of hepatitis B virus infection are nonspecific, so a history of sexual activity or exposure to blood are necessary clues.
Why Vaccinate?
Vaccination involves the injection of a component of hepatitis B virus. The body recognizes this as foreign and initiates the immune response. Immune response leads to the production of antibodies, which are molecules that help the body fight the virus when it enters the body. Vaccination boosts the immune system, preparing the body for a possible attack by hepatitis B virus. A boosted immune system fights off infection quickly and prevents the manifestation of symptoms.
Indications for Vaccination
Vaccination is necessary in people who work in hospitals and medical laboratories because they work closely with blood. The U.S. Preventive Services Task Force recommends vaccination among young adults with no previous history of vaccination. Vaccination is only useful if people are not infected with hepatitis B virus. People who come in contact with infected blood or sexual activity with a person who is known to have hepatitis B virus infection do not benefit from the hepatitis B virus vaccination. For these people, HBIG, or antibodies against hepatitis B virus, is recommended.
Response to Hepatitis B Vaccine
Adequate vaccination of hepatitis B involves three series of injections over time. Following vaccination, the blood is tested to verify immunity against hepatitis B virus; this test involves the measuring of antibodies produced by the immune system after vaccination, says the Joint Committee on Vaccination and Immunization. Low antibody production is an indication of a poor response to vaccination. Poor response to vaccination may be due to advanced age, smoking and morbid obesity. People who are immunocompromised, or have a weak immune system, aren't likely to produce the required amount of antibodies needed.
